At least half of all maltreatment cases in the U.S. occur in the context of substance use disorders. Child welfare agencies play an important role in connecting families to appropriate services within the community. This study will integrate qualitative comparative analysis (QCA) with regression to identify combinations of child welfare investigative and collaborative practices that maximize identification of caregiver and youth service needs and subsequent treatment utilization. QCA is innovative because it accounts for complex interactions between predictor variables. Analyses using data from a 2008-2009 entry cohort of families in the National Survey of Child and Adolescent Well-Being will proceed as follows: Multiple regression will determine the net effect of each practice on specified outcomes. QCA will identify complex combinations of practices that are positively associated with these outcomes. Finally, integration of QCA with regression will determine which combinations of child welfare agency practices maximize treatment utilization for caregivers and children after accounting for the complex survey design of the data as well as individual demographic and case characteristics. This study will yield important substantive findings and is well-aligned with NIDA's strategic goals of improving treatment access and helping prevent addiction in at-risk families.